The present invention relates to a cab for earth-moving machines of the kind comprising the characteristics expressed in the preamble to claim 1.
Earth-moving machines are composed of a frame mounted on wheels or tracks, whereon is pivotally fastened an articulated arm bearing a work tool. In most applications, the work tool is constituted by a shovel or bucket.
In less frequent applications, the tool can also be constituted by other attachments, such as snow shovels, pneumatic hammers and augers.
On the frame is mounted a cab for housing an operator tasked with maneuvering the earth-moving machine.
The cab generally comprises a closed structure having at least an opening, which can be closed with a door, such as to allow operator access. In the cab are mounted a seat and, in front of the seat, control organs and/or pedals to allow the operator to control and maneuver the machine. Although closed, the cab still guarantees good visibility for the operator since it is largely built with see-through materials.
Hereafter, reference shall be made to earth-moving machines of the kind whose frame has two parts: a first part able to rotate about a substantially vertical axis and bearing the cab and the articulated arm, and a second fixed part whereon the wheels (or tracks) are mounted.
Advantageously, the invention is preferably destined to this type of machines. The invention can nonetheless be applied in general to every type of earth moving machine.
As is well known, doors of earth-moving machine cabs must be able to be locked, while the machine maneuvers, in the closed or open position, to avoid being needlessly banged about due to the machine's movements.
To this end, cabs are provided with appropriate latching means.
The possibility to keep the door open or closed meets two different needs of the orator. On one hand, the operator can keep the door closed to isolate him/herself from the noise and dust created by the machine. On the hand, he/she can keep the door open both to climb and descend from the machine more easily, and to allow air to circulate in the cab during particularly warm days.
A first known type of doors provides for the doors to be slidingly mounted on the cab, and to be able to moved from the closed position to the open position, always remaining adjacent to the cab.
A second known type of doors provides instead for the doors to hinged onto the cab according to a substantially vertical axis of rotation about which they can rotate from the closed position to the open position completing a rotation of about 180.degree..
In this second case, doors are adjacent to the cab only when they are in the closed position or in the open position. In any other position they may assume, they obviously project from the cab.
The prior art described, however, has several drawback.
Since in earth-moving machines the cab can rotate 360.degree., an essential characteristic is represented by the operating radius of the machine itself This radius is defined as the radius of the largest circumference described by a point of the cab during the rotation of the cab itself about the pivot point on the fixed part of the frame whereon it is installed.
To make the operation of the machine safer, it is very important that no part of the cab project beyond the operating radius of the machine itself.
If the condition is met, one is guaranteed that during operation there will be no accidental impacts of the cab itself against any obstacle, such as a tree, a post, a wall.
This is important because in case of impact, on one hand the cab would be damaged, on the other the operator's safety would be Jeopardized, as he/she could suffer, due to the considerable backlash, contusions, whiplash or other similar injuries.
The above represents a problem that reflects on machine doors, because, while such doors are certainly within the operating radius of the machines when closed, they are not necessarily within it when open.
In particular, the operating radius becomes a critical parameter for the design of the cab of a machine, when the dimensions of the machine itself are very small. The conditions that the door, in the open condition, must fall within the operating radius is more difficult to meet the smaller the dimensions of the machine.
In particular, for the cabs of mini excavators, so small as barely to contain the operator, the doors made in accordance with the prior art do not, for the most part, fall within the operating radius of the machine when they are in the open position.
As stated, this is a hazard as it risks causing material damage to the cab and it jeopardizes operator safety.